Rotary pump



C. F. WAHTE Get. 29, 1935.

ROTARY PUMP Original Filed Feb. 28, 1930 l w v Patented Oct. 29, 1935 i'PATEN ROTARY PUMP Charles F. Waite, Somerville, Mass.,

assignor of one-half to Archibald W. Johnston, Bridgeport,

Conn.

' Application February 28, 1930, Serial No. 432,061

Renewed January 16 Claims. (Cl. 103-.- 160) The present inventionrelatesto rotary pumps.

. r The objectsv of the present invention are to provide"improvements'in. rotary pumps with a particular view to obtainingadjustment orautomatic control of fiow under varying conditions and alsoto provide a rotary pump capable of producing smooth and non-pulsatingflow of liquid under all conditions.

With these and other objects in view, as will hereinafter appear, onefeature of the invention comprises the combination with a rotarycylinder, a reciprocating piston and eccentric positioning means for thepiston, of a. support for the eccentric means which can be adjusted toany desired position to control the rate or direction of flow of thefluid. In the preferred form of the invention, employed under conditionsof varying pressure or speed, the eccentric support is spring mounted tofloat to aposition determined by the discharge pressure. This featurenot only permits automatic control of flow in accordance with thepressure, but also afiords means whereby the pump is rendered inactivewhen the discharge pressure rises to an excessive value, aswhen thedischarge is blocked. The pump is then permitted to idle but withoutcausing undue agitation of the fluid remaining in the pump, such as mayoccur in the usual by-pass safety valve ordinarily employed in rotarypumps.

Another feature of the invention contemplates the use of a plurality ofpistons working in a single cylinder and controlled to afford an overlapof power whereby the pumpoperates with greatly decreased vibration andimproved smoothness of discharge.

Other features of the invention consist in certain novel features ofconstruction, combinations and arrangement of parts hereinafterdescribed and particularly defined in the claims.

In the accompanying drawing, Fig. 1 is a sectional elevation of one formof pump according to the present invention, being a section on line |-lof Fig. 2; Fig. 2 is a section on line 2-2 of Fig. 1; Fig. 3 is an endview of the casing; Fig. 4 is a section on line 44,of Fig. -3; Fig. 5 isa sectional view of a modified form of positioning means; Fig. 6 is aside elevation of a modified form of the invention employing a doublepiston; Fig. '7 is an end view of the construction shown in Fig. 6; Fig.

v8 is afsection on line 8-8 of Fig. 7; and Fig. 9

- is asection on line 9-9 of Fig. '7.

The pump shown in Figs. 1 and 2 comprises a casing 16, a shaft l2, arotor orcylinder. l4 pinned .to the shaft, and apiston l6slidingly'received' in a diametrical groove I8 of the rotor. The casingis formed with inlet and dischargechambers 20 n and 22 connectingrespectively with inlet and discharge-ports 23 and 24. Between thechambers, r 20 and 22, the casing is formed with sealing 'surfaces 25and 26, which are continuously engaged by the cylindricalsurfaceijotthe-rotor; :The ro- I tor is'continuously rotated bythe'shaft l2 and the piston is reciprocated with respect to the rotor bymeans of an eccentrically mounted shuttle'or block 28. slidinglyreceived in a transverse 1o groove of the piston. The parts thus farde-- scribed are similar to those described in my copending applicationSerial No. 424,208, filed January 29, 1930. The shuttle 28 is mountedfor free rotation on. an eccentric pin 30 which passes through a slot 32in the end'plate 34 of the casing. The eccen-.

tric pin 30 is secured to a control piston 36 which is slidinglyreceived in a housing or cylinder 38 formed integrally with the endplate and having its axis parallel to the center line connecting thesealing surfaces 23 and 24 of the casing. The control piston 36 is boredatone end to receive a coil spring 40 which bears against a nut 42threaded into one end of the housing 38. The spring holds the pin in aneccentric position.

To control the eccentricity of the pin, a pressure passage 44 is coredin the end plate. This passage runs from the discharge chamber 22 to thetop of the housing 38 immediately above-the piston 36. By this means, avariation in pressure acts directly on the piston 36 to vary theeccentricity of the pin and to vary the stroke of the piston, therebyrestoring'the discharge pressure to its normal value. Inasmuch asleakage may occur around the piston 36, a bleeding passage 46 cored inthe end plate runs from the lower end of the housing 38 to the inletchamber 20. The suction of the pump keeps the spring end of the housingdrained, so that the the cylinder and thereby to pump liquid from theinlet chamber to the discharge chamber of the casing. The stroke of'thevpiston, and hence the pressure and volume of fluid handled by the pump,are determined by. the lengthof theslot 32.; If an excessivepressurebuilds up, the con- ,trol pistonis forced by the fluid pressureto a more nearly concentric position. Ii, for example, the dischargeshould become blocked, the pressure will force the pinto a practicallyconcentric position, the pump piston will then assume a halfway positionand will rotate idly 'in the chamber without reciprocating. The spring astrength such as just to balance, under normal running conditions, theforces applied to the control piston by the fluid pressure at one endand the suction at the other end.

It will be seen that under conditions of blocked discharge, wherein thepump rotates idly, there is practically no agitation of the fluid whichremains in the pump, an important feature when pumping materials whichare likely to froth or to separate under mechanical agitation.

Where conditions of varying pressure are not met with, an adjustablefixed eccentric may be employed, as shown in Fig. 5. In thisconstruction, the eccentric pin 30 is mounted in an adjustable piston 52which is similar in general construction to the control piston 36previously described, except that no provision is made for reception ofa spring. The piston 52 is adjustable in the housing 38 of the end plateby means of a threaded screw 54 received in a threaded bore of thepiston. The screw 54 passes through a nut 56 which is received in theend of the housing. The screw has a shoulder 58 bearing'on the inside ofthe nut and has secured to it externally a collar 60. By turning thescrew 54 in or out, the eccentric may be adjusted to any desiredposition. With this means, the eccentric can be adjusted to either sideof the center position, so that the pump may operate to pump fluid ineither direction with the same direction of rotation of the rotor.

In order to provide a greater smoothness of flow than is possible with asingle piston rotary pump, the construction shown in Figs. 6 to 9 isuseful. This construction comprises a rotor 62 of the same general formas the rotor of the pump describedabove, except that it is provided withtwo intersecting diametrical grooves 63 and 64 to receive twointerlocking pistons which have their center lines intersecting at theaxis of the rotor. The casing and end plate of the pump are identicalwith those employed in the single piston pump and are not shown in theseflgures. The two pistons 65 and Stare of rectangular cross-section andeach has a central transverse groove to accomodate a shuttle 68. Thewidth of each transverse: groove and of the shuttle is necessarilysomewhat greater than the width of each piston to allow for the compoundsliding movements of thetwo pistons. The shuttle 68 comprises a squareblock which is of greater width than the width of either piston by anamount at least as great as the length of the stroke. As shown in Fig.6, the shuttle has its corners beveled to permit them to clear theinher; walls of the rotor. As shown in Figs. '7 and 8-, the pistons areplaced across each other with their transverse grooves registering andenclosing the shuttle. The outer piston 66 is provided with an openingIII to permit the eccentric pin 12 to pass therethrough and to bereceived in the shuttle block. The opening 10 is of such a size as topermit reciprocation of both pistons without causing the walls of theouter piston to press on the eccentric pin 12. The pin 12 may be mountedin flxed eccentric positionwith relation to the driving shaft or it maybe mounted as shown in Figs. .1 and 2 in adjustable position.

In operation, each piston works independently 5 of the other. As shownin Fig. 6, the outer piston 66 vertical position and is closing theupper cylindrical surface of the rotor, while the inner piston 65 is inits or halfway position. Upon turning the rotor through an angle of 90,the former piston will turn into the halfway position, and the latterwill assume the position now occupied by the former. Each pistontherefore follows its own series of motions independ- I ently of theother and the two pistons succeed 15 each other at an angle of 90. Eachpiston gives two pumping strokes during each revolution, making a totalof four strokes for the combined pistons. Because of the overlap ofpumping pressure by the double piston construction, pulsations 20 in theflow are effectively eliminated and the pump operates without vibration.For the same stroke as in' the single piston stroke, the capacity isdoubled but if only the same capacity is desired, the stroke may behalved, thereby conduc- 25 ing to simplification of construction andfurther smoothness of operation.

In any of the constructions above described, it will be seen that thepump has the advantage of continuous bearing over large surfaces wher-30, ever sliding contacts are made. Thus, the piston has a continuousbearing with the walls of the groove within which it slides, and theshuttle block has a continuous contact with the walls of the pistongroove. This feature conduces to 35- quiet operation and long wear.

Having thus described the invention, what is claimed is:

1. A rotary pump having, in combination, a

rotor provided with a diametrical opening, a 4.0,

piston slidingly received in the opening and having a transverse groove,a block received in thegroove and having bearing surfaces in continuouscontact with the walls of the groove, an eccentric pin on which theblock is freely rotatable, 45 a sliding mounting to carry the eccentricpin, means for adjusting the position of the sliding mounting to varythe stroke of the piston to vary the fluid volume from zero to maximum,and means connecting said adjustment means 50 for positioning by thedifferential oi the discharge and intake pressures of said pump.

2. A rotary pump having, in combination, a rotor provided with adiametrical opening,- a piston slidingly received in the opening andhav- 55 ing a transverse groove, a block received in the groove andhaving bearing surfaces in continuous contact with the walls of thegroove, an eccentric pin on which the blockis freely rotatable, afloating support for the pin, a spring 60 pressing on the support toposition the pin and means connecting said support means for positioningby the difierential of the discharge and intake pressures of said pumpin opposition to said spring. 65 3. A rotary pump having, incombination, a rotor provided with a diametrical opening, a pistonslidingly received in the opening and having a transverse groove, ablock received in the groove and having bearing surfaces in continu-- 7ous contact with the walls of the groove, an eccentric pin on which theblock is freely rotatable, a floating support for the pin, a springpressing on the support to position the pin, an adjustable stop for thesupport to determine the '16,

Cir

maximum eccentricity of the pin and the maximum stroke of the piston tovary the fluid volume from zero to maximum, and means connecting saidadjustment means forpositioning by the differential of the discharge andintake pressures of said pump.

4. A rotary pump having, in combination, a rotor provided with adiametrical opening, a concentric shaft for the rotor, a pistonslidingly received in the opening and having a transverse groove,eccentric positioning means including a shuttle block received in thegroove, a pivot for the block, a sliding mountingfor the pivot to permitvariations of stroke of the piston,' and means controlled by thedifierentials of the discharge and intake pressures for positioning theeccentric means.

5. A rotary pump having, in combination, a casing having suction anddischarge chambers, a rotor, a pumping means in the rotor, an eccentricpivot engaging the piston, an automatic sliding control piston to whichthe pivot is secured for exclusively adjusting said pumping means fromzero to full capacity, a housing for the control piston, a connectionfrom the dis charge chamber to the housing to apply the dischargepressure to one end of the control piston tending to move the pivot to aposition concentric with the rotor, a spring acting on the opposite endcontrol piston and yieldingly resisting the movement thereof, and meansfor bleeding the housing of fluid which leaks past the control piston.

6. A rotary pump having, in combination, a casing having suction anddischarge chambers, a rotor, a pumping means in the rotor, an eccentricpivot engaging the piston, an automatic sliding control piston to whichthe pivot is secured for exclusively adjusting said pumpirg means fromzero to full capacity, a housing for the control piston, a connectionfrom the discharge chamber to the housing to apply the dischargepressure to one end of the control piston tending to move the pivot to aposition concentric with the rotor, a spring acting on the opposite endof the control piston and yieldingly resisting the movement thereof, anda bleeding connection from the suction chamber to the housing at thespring end of the control piston.

7. A rotary pump having, in combination, a casing having suctionand'discharge chambers, a rotor, pumping means reciprocating piston inthe rotor, an eccentric pivot engaging the piston, an automatic slidingcontrol piston for exclusively adjusting said pumping means from zero tofull capacity, a housing for the control piston, the casing and housinghaving passages connecting. the suction and discharge chambersrespectively with opposite ends of the control piston, and a springacting on the piston to press the latter against the movement tended tobe imparted thereto by the fluid pressure applied thereto.

8. A rotary pump having in combination, intake and discharge ports, arotor, a piston mounted for pumping reciprocation in said rotor,automatically adjustable eccentric positioning means for said pistonadapted to determine the pump-. ing capacity of said piston from zero tofull capacity by varying its degree of reciprocation relatively to therotor, resilient means normally urging said eccentric positioning meansto an extreme eccentric position corresponding to full pumping capacity,an independent pressure passage in the pump between said eccentricpositioning means and the discharge outlet, a second passage betweensaid positioning means and said Y intake port, whereby the differentialof the discharge pressure induced by the pump relatively to its intakepressure will tend continuously to 5 urge said eccentric means to anon-eccentric and non-pumping position, the said resilient means and thesaid differential pressure being thus exclusively effective through saideccentric positioning means to control the pumping capacity of said 1pump.

' 9. A rotary pump having in combination, intake and discharge ports, arotor, pumping means mounted for pumping movement in said rotor,

adjustable positioning means for said pumping means adapted to determinethe pumping effort of said means by varying the movement thereof, saidpositioning means being operable to vary the pumping volume between zeroand full capacity,

a spring adapted to press said positioning means 2 into full pumpingposition, a fluid pressure control for said positioning means comprisinga pressure passage between the discharge port of said pump and saidpositioning means and a second passage between said positioning meansand the intake side of said pump, whereby the differential of the intakeand discharge pressures will urge said positioning means against saidspring to a non-pumping position, the said spring and the diiferentialof the intake and discharge pressures being thus exclusively efiectivethrough said positioningmeans to control the pumping capacity of saidpump.

10. A rotary pump having in combination, in-

take and discharge ports, a rotor, pumping means mounted for pumpingmovement relatively to said rotor, adjustable eccentric positioningmeans for said pumping means adapted to determine the pumping capacityof said pumping means by varying its degree of movement relatively tothe 40 rotor, said positioning means being operable to vary the pumpingvolume between zero and full capacity, a spring adapted to press saidposition-,- ing means into full pumping position comprising a fluidpressure control for said positioning means, 45.

a pressure passage between the discharge port of said pump and saidpositioning means and a sec ond passage between said positioning meansand the intake side of said pump whereby the difierential of the intakeand discharge pressures will to urge said positioning means against saidspring to a non-pumping position, the saidi-spring and the differentialof the intake and discharge pressures being thus exclusively eifectivethrough said positioning means to control the pumping capacity of saidpump, whereby said control means will be afiected by the differential ofthe discharge and intake pressures of said pump for adjusting saidpositioning means in opposed relation to said spring means.

11. A rotary pump having in combination, in-

take and discharge ports, a rotor, pumping means difl'erential of theintake and discharge-pressures will urge said positioning means againstsaid spring to a nompumping position, the said spring and thedifferential of the intake and discharge pressures being thusexclusively effective through said positioning means to control thepumping capacity of said pump, whereby said control means will beaffected by the differential of the discharge and intake pressures ofsaid pump for adjusting said positioning means in opposed re lation tosaid spring means.

12. A rotary pump having in combination, a rotor, pumping means mountedfor pumping movement relatively to said rotor, adjustable positioningmeans for said pumping means adapted to determine the pumping capacityof said pumping means by varying the degree of movement relatively tothe rotor, said positioning means being operable to vary the pumpingvolume between zero and full capacity, spring means adapted to urge saidpositioning means in a full pumping direction, means connecting saidpositioning means for operation by the diiferential of the discharge andintake pressures of said pump in a direction opposite the pressure ofsaid spring, the said spring means and the diiferential of the intakeand discharge pressures being thus exclusively effective through saidpositioning means to control the pumping capacity of said pump.

13. A rotary pump having in combination, intake and discharge ports, arotor, pumping means mounted for pumping movement in said rotor,adjustable positioning means for said pumping means adapted to determinethe pumping effort of said means by varying the movement thereof, saidpositioning means being operable to vary the pumping volume from zero tofull capacity, spring means adapted to press said positioning means intofull pumping position, a fluid pressure control for adjusting saidpositioning means in opposed relation to said spring pressure todecrease the pumping capacity as the pressure is increased andcomprising a pressure passage between the discharge port of said pumpand said positioning means and a second passage between theintake sideof said pump and said positioning means, whereby the differential of theintake and discharge pressures will urge said positionirm means, wherebythe differential of the pumping position, the said spring and the dif-Ierential of the intake and discharge pressures v 7 2,018,692 and theintake side of said mp whereby the being thus exclusively effectivethrough said positioning means to controlthe pumping capacity of saidpump.

14. A rotary pump having, in combination, a

rotor provided with a dlametr'dcal opening, a pis- 5 ton slidinglyreceived in the opening and adapted to reciprocate relatively to saidrotor to contribute a pumping action, an eccentric pin for determiningand varying the throw of said piston as said rotor rotates whereby tovary the pump- 10 ing volume, a floating support for the pin, a springpressing on the support to position the pin, and means connecting saidsupport means for positioning also by the differential of the dischargeand intake pressures of said pump. 15 15. A rotary pump having,- incombination, a casing having suction and discharge chambers, a rotor, anadjustable pumping member in said rotor, means for adjusting saidpumping member to vary its pumping capacity from zero to 20 -fullcapacity, a sliding control piston by which said adjusting-means areoperated, a housing for the control piston, the casing and housinghaving passages connecting the suction and discharge chambersrespectively with opposite ends of the 5 control piston, and a springacting on the piston to press the latter against the movement tended tobe imparted thereto by the fluid pressure applied thereto.

16. A rotary pump having in combination, in- 30 take and dischargeports, a pump body member, pumping means mounted for pumping movementrelatively to said pump body member, automatic. adjustable positioningmeans for said pumping means adapted exclusively to determine the 35pumping capacity of said pumping means from zero to full volumebyvarying the degree of movement thereof relatively to the pump' bodymember, a spring of predetermined tension adapted to press saidpositioning means into one extreme position corresponding to fullpumping, and means connecting said positioning means for operation bythe differential of the discharge and intake pressures of said pump intoan opposite extreme position correspondingto zero pumping by saidpumping means, the relation between the spring tension and the possibledifferential pressure which may be developed by said pump being suchthat the said differential pressure may move said positioning meansagainst the spring into a position corresponding to zero pumping.

CHARLES F. WAITE.

